Diesel Fuel Additives... Necessary?

[PaulDaniel]

I recently bought a 1994 Catalina 270 that has an inboard Perkins M20 (3-cylinder, 18 HP) diesel.

Please feel free to weigh in on any or all of these questions:

1) Should I use a lubricity additive? In 2006 they started selling Ultra Low Sulphur Diesel, which reduced lubricity in fuel. I'm pretty sure that I should use a lubricity additive. Or perhaps a multipurpose additive that has a lubricity component.
2) Should I use a "stabilizer" additive? A lot of people say diesel doesn't go bad. It is hydrophobic. It has a higher flash point so you don't have to worry about the more volatile components evaporating. But I believe it can still oxidize. Even though fuel may not "god bad" the way gas will, it may degrade over time. At least that's my understanding. Would a stabilizer additive help with this or is it just snake oil? There is "Stabil for Diesels", but I'm not sure how this product works or if it is actually effective.
3) Should I use a biocide additive (in order to prevent fungal growth in the tank)?
4) What about a multipurpose additive like Hot Shot's or Archoil?

 

[Don S/V ILLusion]

Opinions vary.

i use a cetane booster but nothing else In fresh fuel.

if you dont use much fuel, both ASTM and Navy studies conclude “diesel fuel gets old” after 6 months. Whatever you infer from that… stabilizers might help but never proven to my knowledge.

 

[Terry Cox]

Good morning, Paul. Over the years I have used a biocide added to our diesel fuel tank to reduce the chance of fungal growth. I will never ever use any other kind of fuel additive regardless of what it may or may not do to an engine's performance.

 

[kappykaplan]

Should I use a biocide additive (in order to prevent fungal growth in the tank)?

Absolutely! I add biocide every time I refuel.

 

[Tally Ho]

I have a small 19 gallon diesel tank and that can last me a season here on the Great Lakes. As you can see, I am not refilling the tank very often. I usually top the tank off in the fall before haulout, and add a bit of Biobor Jr. to keep any growth in the tank at bay. I don't add anything else.

Practical Sailor had an article that discussed various additives…

Diesel Additives - Practical Sailor

Since 1974, Practical Sailor’s independent testing has taken the guesswork out of boat and gear buying.

www.practical-sailor.com

Greg

 

[Richard19068]

From a "Practical Sailor" article May 2024.
"If cetane is not a big issue for you, and we don’t think it is, then Biobor JF will control bugs and add lubricity, and STA-BIL® Diesel will stop corrosion."

Diesel Performance Additives - Practical Sailor

We think of ourselves as sailors, but we all depend on reliable power to propel us in and out of harbor, through calms and often to assist in storms.

www.practical-sailor.com

And from April 2021:

Star Tron Diesel + Biobor JF
A top performer in anticorrosion tests and anti-aging tests, Star Tron Diesel also performed well when used in combination with Biobor JF. In biocide testing trials (Star Tron is not marketed as a biocide), it showed properties that complimented Biobor JF (killed different strains), making the pair a powerful one-two punch.
Bottom line: While this blend requires adding two products, based on our testing, it is the Best Choice overall.

Additives vs. Gum, Sludge - Practical Sailor

Since 1974, Practical Sailor’s independent testing has taken the guesswork out of boat and gear buying.

www.practical-sailor.com

 

[jssailem]

Congratulations on the new (to you) Catalina 270. It is a fun boat.
Perkins are good engines. Mine is 52 years old. It has just been rebuilt. The mechanic who helped with this rebuild says it will be here and going longer than I will.

I have been down the rabbit hole on diesel fuel issues. There are several resources for you to explore, much like the options with gas and cars.

How you plan to use the boat should guide you in maintaining your fuel system. If you plan to run the engine to move in and out of the marina, you may not want to put more than a few gallons in the tank to keep it fresh.

Long cruising trips that would require multi-hour engine usage would be when I would fill the 17-gallon tank.

Keeping water out of the fuel tank is crucial for maintaining clean fuel.

That said, I have been able to manage my 85-gallon tank using the fuel additives discussed in Practical Sailor.

I also have a fuel filtering system that I have posted here on SBO. It would be overkill for a 270.

The fuels we see in the Puget Sound contain additives. The key is to replenish boat fuel where the Marina supply tanks are frequently refilled. This optimizes your opportunity to get clean, fresh fuel.

Reading resources.

• Real Story of Bad Diesel Fuel - Diesel Fuels
• https://www.fuelright.com/
• Diesel Fuel Additives Part I – Editorial: Following Manufacturer’s Instructions - Steve D'Antonio Marine Consulting
• Diesel Fuel Additives – Part II - Steve D'Antonio Marine Consulting
• https://stevedmarineconsulting.com/wp-content/uploads/2021/10/Diesel_Primer115_04Rev.pdf
• https://stevedmarineconsulting.com/wp-content/uploads/2014/03/FuelPolishing_PBB112_opt.pdf

 

[David in Sandusky]

Over 25 years, the only additive I have used is biocide after we pull the boat for the winter. Diesels keep on working if we ensure enough lubricating oil, and change the filters from time to time.

 

[Dalliance]

I use about 15 to 19 gallons per season with a 12 gallon tank that’s always topped off before winter storage.

I have been adding Stabil and Boibor JF with every refueling for nearly 20 years on instruction of the previous owner who did the same as long as he had the boat. Though I switched out the Stabil for Biobor MD last year because it claims to do everything that Stabil does plus a few other things like reducing soot. I’ve been told that the diesel I buy at the fuel dock has all the additives I need, but I don’t think the additional can do any harm and it makes me feel I’m doing all I can do.

Key is keeping water out of the tank in the first place. My fuel fill is inside the aft lazarette which helps and I added a high loop to the fuel vent line in the coaming above the through hull vent as well as an H2Out desiccant fuel vent dryer.

 

[CYQK]

Power Services 1)Cetane Booster 2) Biocide

Pay attention to the ratios recomended to add ,good for ever

 

[PaulDaniel]

Thanks everyone for the input! I have decided to use Biobor JF and Startron Enzyme treatment.